What do you think of this design? Mini Cargo Commuter Bike

I am not a framebuilder but am hoping to attempt my first this winter. Lots to talk about there and I'm not going to bother you with it, at least not right now. For now, i'm interested in feedback on my design.

(SKIP THIS IF YOU'RE ADD)First, the reasoning and experiences leading up to it. My wife and I each have longtail cargo bikes right now. We like them a lot in many ways, and we love what we can do with/on them, but they are also a pain in the butt in other ways. They take up a lot of space in the garage and can't be hung on the rack with the rest of our bikes. We can't put them on our roof-rack and take them places. They can't be put on a bus rack. For my wife, they are heavy, difficult and awkward to move around and deal with (she's not very strong). They also don't handle as nicely as a normal bike. Lastly, we find that we very rarely use their full cargo capacity, and could get by with less.

So i've been thinking about what would work better. A regular bike with a couple large panniers and a large front basket would do pretty well, but that's too easy! Also, while you can fit a lot of small items in the panniers, it's hard to fit one large item. Front baskets make the bike tip over and make the steering difficult. That led me to thinking about cycle trucks with their frame-mounted front racks mounted low over 20" front wheels. Then i thought why not do the same in the back as well--another 20" wheel and another large and low rack. Some googling revealed that i'm far from the first to think this might be a good combination and i found several bikes that resemble very closely what i was envisioning.

I contacted a few of these builders and they were able to give me some direction in sorting out geometry. I did a lot of research and found tons of info regarding bicycle geometry but it was almost without exception written assuming a 26-29" wheel size and i was unsure if it could be applied directly to a bike with 20" wheels or if i would need to change things. Researching mini velos and folding bikes provided some help as well, but there is far less information about those than about "normal" bikes.

Here's my design. Please let me know what is stupid and should be changed or what could be done better. There are a few design compromises i'm aware of but have chosen for important reasons:

--The seat tube is cantilevered WAY out past the mixte style seatstays. This is because very low step through height is critical and because i wish to use a standard 27.2 x 350mm seatpost. I'm thinking of using a straight guage 4130 tube 1-3/8" x .095" (34.9 x 2.4 mm) tube for the seat tube, with a sleeve in the top 4-6" to fit a 27.2 post. This is one of the things i'm unsure of.

--The chainstays are abnormally long. This allows for an e-assist battery to be mounted between the seat tube and the rear wheel, and also allows for lots of heel clearance for panniers and other rear loads.

--Racks: Bikecad only displays relatively standard racks. These are just placeholders for whatever rack design I eventually decide on. The front rack will be frame mounted (not fork) and both racks will be removable so that they can be replaced with a better design or a different modular accessory.

I'm hoping the bike can be fairly suitable for both my wife (5'5") and I (6'0"). I'm thinking of using a Montague Octagon extendable steer tube to allow for quick adjustment of handlebar height by several inches. I had thought about using Workcycles' Adaptive Seat Tube design as well, but have decided against it for now, mostly for the sake of simplicity since i've already got a fairly unconventional build ahead of me.

I'd like to build it up 1x7 (or IGH if budget permits) with a 11-28 cassette, thumbshifter and BB7 brakes. It will probably get e-assist (my wife and I are big fans of this for town/utility bikes). At some point i'll need to select some dropouts that might accommodate all those options.

These first two pictures show the bike setup for my wife's height, the third is for my height. The only difference is seatpost and steer tube extension.

I like it. I'd probably build the front rack into the frame though so that it doesn't affect steering. Right now a drop bar minivelo is my only bike (the rest are overseas) and I really like it. Couldn't think of any better bike for tight urban maneuvering. The quick acceleration and agile handling are way more noticeable than any theoretical loss of rolling resistance or whatever. Have you seen this longtail mini from the oregon manifest?

Two more mini cargo bikes

There's a couple i haven't seen before, thanks. One thing that surprises me a little about many of these bikes is that they don't seem to make a serious effort to get the racks as low as possible. If you aren't doing that, what's the point of the little wheels? I really want my racks to be as low as possible.

The other is that a lot of them just don't have good style. This is of course, completely subjective, but I think my design looks nicer than most of the bikes in this category. Not that it's amazing, but I was trying to make it more masculine than some and less goofy than others. Whether or not I've succeeded at all is entirely debatable.

Omiak, in my first post i linked to the quixote bike and mentioned that even though the front rack is shown attaching to the fork, that it actually would be frame mounted. THanks for the feedback though.

What do you mean by "cargo"?

I have ridden a cycle-truck type bike similar to what you've posted here and while it's better than carrying your stuff in a backpack, it's not at all a true "cargo" bike IMO, because it's pretty much impossible to carry heavy stuff with any amount of confidence. You're not going to throw a 40 pound bag of dog food on there and really be able to ride it because the load is way too high up.

So if you want to carry a few bags of groceries, great idea. If you want to haul heavier or bulkier stuff, and you need to save space in the garage, get a BOB or some other trailer and just use a normal bike to pull it.

Omiak, in my first post i linked to the quixote bike and mentioned that even though the front rack is shown attaching to the fork, that it actually would be frame mounted. THanks for the feedback though.

Thanks Walt. What we've found is that we very rarely carry heavy loads. 90% of the time we're carrying a small amount of groceries or just whatever we want to have with us for a day of running around town (water, extra clothes, towel, sunscreen, picnic stuff, etc), most of the stuff is not heavy.

I love how the donkey bike is made to stand up on its rear wheel and rack! I'm definitely going to incorporate that into the design. I've seen longbikes that do that too (yuba maybe?) but i think that would require more than an 8' ceiling.

I made a mini-velo "cargo" bike and liked it a lot. I could carry about 50 pounds in front.

As you note, you can get the cargo lower down. The bike is also smaller overall, which helped bringing it inside places or putting it in cars. The small wheels are tough and I never worried about them going out of true.

You have to think carefully about front-end geometry. I had very little trail, and combined with the small wheel, the handling was not great unleaded. WIth a load on the front it was a lot better.

As for the rear end, I understand that the long stays are a requirement, but it looks like you are throwing a lot of weight onto the front wheel. You might want to think about how that will effect your steering.

Finally, tires are a big issue. Since the wheels are so small and stiff, and cargo bike frames need to be stiffer, your tires are going to be soaking up a lot of the bumps. Make sure you get good ones that are supple and yet don't squish out a lot under load.

Great feedback Jim, thanks! Do you recall what the actual trail number was on your frame?

Perhaps having the long stays on my bike, and the resulting increased weight on the front wheel will act to improve handling in the same way that your bike handled better with a load on the front rack? As long as it is not then too much weight when there is a front load in addition.

I've updated my design a bit, and also gotten bikecad to display a frame-mounted front rack. I'm not sure how exactly that front gusset will be formed but i'll need to have something like that to support the head tube.

I think i'm getting close to a point where i need to start picking out tubes and dropouts and thinking about details like seat binder etc. I'm not sure exactly how to progress from here. How does one select tubes? I'm not really concerned about weight. I want durability and ease of construction. What do i use for seat stays on a mixte like this?

Also, i'd like to use disc brakes, what hardware do i need to attach to the frame/fork and how do i align it?

Afraid to say i haven't progressed past what's here. Life and work and all that, but also a little bit unsure of how to get started. Still thinking about it but haven't done anything physical.

I've been considering just modifying something like a folding bike or a Origin-8 Bully also, instead of building completely from scratch. Haven't been able to find the right thing yet, in steel, at the right price. A bully would be perfect but they can't be found anymore.

Were you going to weld this up yourself or did you have a guy in mind? I have a few ideas of things I'd like to do, but don't have the $$$ to have Wade or Customfab. Unfortunately I don't have the skills and/or skills to do it myself

The plan was to fillet braze it myself. That may or may not ever happen. If i'm serious about the bike probably the fastest way to get it would be to pay an actual builder to make it for me. I heard that Wade is not making bikes any more. I haven't actually spoken to him about it.

I chatted a bit with Rick at 369 Fabrications about other projects and saw some longtail cargo bikes that he built. They looked very nice. He may be a good candidate to build a custom bike.

Yes I live in Bend and saw Wade comment on this thread. I looked on Wades Twitter feed and saw several dual 20" bikes that looked pretty nice (in Ti!). I'm thinking something like a xtravois 2.0 with a da Vinci tandem drivetrain with e-assist but in a traditional diamond frame vs x-frame.

I've been fillet brazing racks, and brazing them to bike frames, but have not made a bike frame.

Do you have a sketch of your plan? You're talking about a 2-person bike? I'd love to see a pic of what you're talking about. Maybe we should get a beer/coffee sometime and collaborate.

No, no sketch of the bike, although I did try using Bikecad.ca for a few minutes but it seems (like anything) it takes some practice and knowing what the f@#& your doing to get anywhere!

The bike I have in my head is for a single person, but uses the da Vinci tandem drivetrain with the stoker position being motivate by a ~750-1000W Hub motor similar to the StokeMonkey. The thing about the StokeMonkey (Xtravois) is that it is linked to the pedals, so anytime you use the Electric Assist, it spins the petals. No this isn't a big problem as it is a Bicycle first, but I can see times when I would like to use just the Epower (like pulling away from a stop).

I want to use the hub motor thru the gears like the Xtravois/Stokemonkey (brilliant!) and I figure if I'm building (or having built) a frame I should get exactly what I want.

I just became aware of the da Vinci tandem drivetrain a few weeks ago looking around the internets and then I saw one in the metal yesterday @ Gear Pedaler in Bend! Really slick system w/very little drag. Go check it out.

I'd be down with getting a beer/coffee sometime, but I don't have any drawing/sketches FYI.

Jeff

PS I think I saw you had 2 e-cargo bikes, which ones? My dad has an el Mundo and it's pretty sweet, but BIG and I think overbuilt for what I'm thinking.